I don’t know where you are but look up "State Seal" corp. I went down there with a handful of seals & bearings & the counter guy was very nice. He had everything I wanted & some with more than 2 designs for the drive shaft seal. They brought out the mic & pulled everything from the shelf, no problem! I even ordered dups of some stuff as a guy never knows when a part is pulled from stock forever. Mine was a 1953 Firestone 7.5 HP motor.
Good Luck
Jeff